The Blue Danube, made famous by Strauss, may be blue at some times, but as we wend our way northeastward in November on the Viking Longship Jarl, it varies between slate gray and gray-green, regardless of whether the sun is out or the clouds are lowering. This particular river cruise makes its relentless way downstream from Nuremberg—site of the famous War II war-crimes trials—through Germany, Austria, alongside Slovenia and into Hungary, ending finally at Budapest.

A few years ago Viking was a smallish company, which had a dozen boats plying the waterways of Europe. In the ensuing years, it has exploded to over 65 boats sailing the rivers of Europe, Russia, Asia and Egypt. Their newest boats, the Longships, named after Norse gods, are 135 meters long, with four decks, and accommodate almost 200 passengers in a goodly amount of comfort and luxury. Cabins are small but very well appointed and intelligently thought out—and of course, one can "buy-up" to larger accommodations and suites. The front half of the main and upper deck contain restaurant, bar & large lounge, and informal grill-room, the Acquavit Terrace, respectively. The top deck is the sun-deck with the bridge in the middle, and the lower deck contains a few cabins, and crew quarters, galley and maintenance areas. The bridgehouse has a fascinating facility to accommodate low bridges—it drops halfway down into the deck on a hydraulic system.

The daily drill is to sail a fair bit at night, take breakfast at anchor at the next sightseeing town, shore excursions to visit historic towns, monuments, churches, monasteries and the like. Lunch sometimes on shore, always available on ship. Afternoon mostly at leisure, either in town or on ship—sometimes gazing out while sailing past the countryside. Cocktails and daily briefing at 7, followed by dinner either in the restaurant, or if a lighter meal desired, in the grill. Fare in the restaurant is a combination of buffet, and choice of several entrees delivered from the kitchen, and is uniformly of high quality. We had hoped for a galley tour, but the kitchen staff is just too busy feeding a couple hundred passengers, plus crew.

We were warned a week in advance that the Danube was experiencing extreme low water in some places—no rain for months, apparently—and that we would likely have to debark at least once, and change to a different ship past the un-navigable portion. Quite complicated logistics that Viking seems to have mastered well. We did have to pack up and move out at Regensberg, spend the day on a bus-tour of several sites, a short day-sail on a local boat up the beautiful Wachau Valley, and embark on the Viking Atla—an identical ship, in the same cabin, at Melk, past the low water at Passau. Chantal, the effusive six-foot Dutch program director, and Martin, the gregarious British concierge came with us, and presumably the Atla's PD and concierge went the other way with their group of passengers.

We board the ship at Nuremberg, the second largest city in Bavaria. Nuremberg, founded in 1050, features medieval architecture, the fortifications and stone towers of its Altstadt, which contains the central market square and Frauenkirche, a 14th-century Gothic church. It’s also the site of the Christkindlsmarkt, the annual Christmas market, which is not open yet this season. The Palace of Justice is the site of the historic Nuremberg War Trials after WWII, and a visit to the courtroom is quite sobering. At the northern edge of the Altstadt, surrounded by red tile-roofed buildings, stands the imposing Kaiserburg Castle, which was bombed to rubble in the war, and restored afterward.

Another somber place to visit a few kilometers out of town are the Nazi Party Rally Grounds, which was the site of six enormous rallies between 1933 and 1938—up to 150,000 people at a time. The entire place, building and grounds, was designed to both intimidate and demonstrate Nazi National Socialist power to the world. The massed stormtrooper scene in the new Star Wars movie, with black and red banners, the huge crowd addressed by a raving General Hux is clearly intended to simulate Hitler ranting to the multitudes at those Rally Grounds.

After touring, we return to the ship in time for cocktails and our first daily briefing by Chantal, our cruise’s Program Director, as the Jarl sets sail downstream.

Regensburg is a beautiful romantic town overlooking the Danube. It was established in 179 as Castra Regina for the Roman Third Italic Legion. By the 6th century it was a fortified hilltop town, and was the first capital of Bavaria. Regensburg is considered one of Europe’s most well-preserved medieval cities, with a collection of towers somewhat reminiscent of Sienna. It contains one of the largest and best-preserved groupings of 13th and 14th-century church spires and patrician houses in Bavaria—all of which resulted in the old town being named a UNESCO World Heritage Site in 2007.

We wander the streets and narrow lanes, stroll the Christmas Market, cross the 12 C. Stone Bridge, currently under reconstruction, spend time in St. Peter’s Cathedral and end up sitting at outdoor picnic tables at the Alte Wurstkuchl—the oldest restaurant in town, dating to 1146. Their tasty specialty is small charcoal-grilled pork sausage served over sauerkraut with crusty rolls and sweet mustard, and they serve some six thousand of them per day! Washed down by good German beer, of course.

After we pack up to route around the low water, it's a fairly scenic bus ride to and up the beautiful Wachau Valley—another UNESCO World Heritage Site—to the head of the valley at the town of Krems. There we pick up a day boat, and meander through the steep terraced vineyards, pine forests and rocky cliffs past the charming villages of Dürnstein—where Richard the Lionhearted was imprisoned in 1193 during the third crusade, and ransomed for a vast amount of gold. While we sail past the picturesque villages of Weissenkirchen—named of course for its white church, and Spitz we enjoy a lunch of Weiner Schnitzel and the local white Gruner Veltliner. We debark at Melk, and head up to the massive Melk Abbey, a Benedictine stronghold that has loomed over the Danube for 900 years. The original abbey was destroyed by fire in the 1800's and what was rebuilt is completely Baroque. Our guide leads us through the art-lined Imperial corridor, the imposing Marble Hall with an impressive 18th C. ceiling fresco, lovely floor-to-ceiling book-filled library and the magnificent Baroque abbey church with its 200-foot-tall dome and twin towers.

We board the Viking Atla at the Melk dock, meet the captain and senior crew, and immediately set sail for Vienna. We were last there a dozen years ago, in the dead of winter, and had the impression of a drab, dreary monumental city. We must have had some sort of blinders on not to recognize the glory of Vienna. The next day we tour the city’s baroque architecture around the Ringsstrasse, including the Opera House and Hofburg Palace for an hour, and then embark on foot to wander the pedestrian zone inside the Ring. Through the Palace, we leave the walking tour for a time to take in the morning exercise session of the famous white Lipizzaner stallions, and then meander through the upscale shopping zone to re-join the group for a tour of the imposing St. Stephan’s Cathedral.

We dine off-ship at The Bank restaurant in the new Vienna Park Hyatt, set in the eye-popping marble banking hall of a century old temple to commerce. The huge open kitchen is set up on the former officer's platform, with all the intense kitchen action in plain site. A delicious rich beef broth with tiny rolls of beef tongue and small dumplings is a great start. I move on to the most perfect, shattering-crust Weiner Schnitzel, and Troy has a succulent baby roast hen with root vegetables. Highly recommended.

Returning to the ship for a nightcap, the captain sets sail, and we travel all night, and through the morning, at low speed due to the dangerously low water, arriving at 3 pm at glorious Budapest. We are very lucky, as we learn that the ship ahead of us was turned back mid-journey by the "water police" and that a ship heading south from Buda was similarly stopped. When I asked the captain how we managed, he replied in very rough English "I sail dees river two dozen year--I know better than poleez".

We dock on the Pest side, and bus up to the top of Buda for a walking tour through the historic Castle Quarter to Trinity Square with its neo-gothic Matthias church and the Fisherman's Bastion, a two-level viewing rampart interspersed with seven conical towers. After wandering the ramparts of the Bastion for a stunning view of the river and Pest side, we quickly get tickets to take advantage of the last 20 minutes of opening of the church, and how lucky that we do—the interior is one of the most magnificent we've ever seen. The interior of the Matthias Church is fantastically decorated on walls and columns with colorful patterns and motifs that were found on original stone fragments. The walls are richly frescoed, and there is are magnificent stained glass windows. It's so very unusual and extraordinary—like no church we've encountered.

At 10 pm the Atla sails out for a glorious night tour of Budapest—past the Mathias Church, Fisherman's Bastion and Buda Palace high on the Buda side, under the historic Chain Bridge, and by the huge Gothic Hungarian Parliament—one meter longer than Westminster—State Opera House and Hero's Square. Budapest's electric bill must be enormous—absolutely everything is fantastically uplit at night.

The cruise over the next morning, we transfer for a final day and night to the Four Seasons Budapest, set in the historic Art Nouveau Gresham Palace, originally built by the British Gresham Assurance Co. as its Hungarian headquarters, with luxury apartments and shopping hall. The building was derelict after many years of neglect, and was acquired to be renovated in 1998. The restoration took until 2004, and resulted in a magnificent lobby with a soaring arched iron and glass ceiling, swirling mosaic floors, and beautifully crafted gleaming wood walls. Rooms are elegantly appointed, as one would expect, and ours on the top floor looks out onto the Danube and up to the Buda side.

It's cold, windy and rainy as we walk the pedestrian Váci Utca to the Christmas Market at Vörösmarty Square. Christmas Markets in Europe go up in late November—this one comprises individual log-forest-hut style stands selling crafts, gifts and foodstuffs, with those around the edge given over to meals to go: fried flatbread covered with cheese and sour cream, rolled flatbreads filled with meat and cabbage, enormous sausages, pretzels, roast chicken and duck, and huge iron vats filled with bubbling stews, Hungarian goulash, and one labeled "rooster testicle stew"—we think that must be a joke. Of course there are beer stands, mulled wine stalls and temporary weinstubes. It's a shame it's raining, as we'd love to have a moveable feast from the market stalls.

We had reserved timed-tickets to visit the Parliament building, which was competed in 1896 with the design the result of an international competition. It is mostly Gothic Revival in style, resembling Westminster in London. The most interesting tour is of the Baroque and Renaissance interior—long hallways filled with frescoes, statues and stained glass windows; a high gilt central dome, beneath which sits the Hungarian Crown and Scepter, guarded by two kepi-topped soldiers who goose-step to change position and salute with swords every 15 minutes. The lobby of the Upper Session hall is ringed with small statues representing every trade and profession in Hungary. From the lobby we step into a box-view of the session hall itself, U shaped with 200 green-leather chairs and desks tiered down to the red-leather inner ring of what was the Cabinet. The Parliament was obviously built well before the 1956 revolution, when Hungary became a republic, and contains two session halls—one for commons and one for lords. Today, only the southern commons hall is in use, as there are no more lords, and the northern hall is rented out for conferences. There is a most interesting museum of the history, architecture and construction of the building, before the obligatory exit through the gift shop.

We take our final dinner in the hotel restaurant, Kollazs at a window table looking up at the nightime Buda tableau, and dine on beef consommé with morel mushrooms and bits of beef tongue, wonderful sweetbread ravioli in an intense veal reduction sauce, and bone marrow served on oxtail ragu with horseradish cream sauce. The food is fantastic, and service friendly and efficient--another hotel restaurant highly recommended.

Budapest is an oft overlooked destination--many people choose Prague as their first Eastern European destination, and our last experience there a year-plus ago is that it is much less interesting, and much more highly touristy that Budapest—a not to be missed stop.